Simon Emil Koedel
Simon Emil Koedel was a spy for Nazi Germany in World War II. A German Navy crew member, He came to the U.S. in 1915, jumping ship as it were. Nothing indicates that he was placed intentionally as a sleeper. In the contrary case he would inevitably have been on some record and would have been found out, as so many others were. We know very little about this man, but he was in all probability a volunteer, who discovered his love for the German cause late in life. He was not a Nazi, or if he was, he never showed it.
Koedel knew what was good for him. He stayed well clear of the many displays of German folklore and the host of Nazi sympathizers that there were in the US in the days before the war. When WWII came, he was already an old man. That helped maintain his incognito. Nor did he ever associate with other German spies in the US, an altogether incompetent lot. Koedel used his stepdaughter to spy on US and other seamen while in port in New York. He monitored American ports and US military suppliers. One of the most successful spies of the war, Koedel obtained and forwarded to Germany volumes of information about US companies involved in the war effort over many years, but also of Policy, decisions made and to come; information which he obtained by posing as a concerned citizen. He worked on base of a "shopping list", didn't take No for an answer and often wrote to Congressmen and other highly regarded persons who unwittingly helped him through otherwise closed doors.
The scheme Koedel used was ingeniously simple. He left the information in the original envelope, which bore the sender address of US Congress or other reputable markings, and merely changed the destination address to the letterbox in Sweden used for that purpose. That address belonged to Heinrich Himmler, the Reichsfuehrer SS. The US stamps and postmarks were all genuine; the decoy was never challenged. In particular, British censors on the Bermuda islands never opened the letters or researched the backgrounds.
The fact that Koedel worked for the SS rather than for the notoriously inept Abwehr establishment increased his longevity. Abwehr officials had the nasty habit of betraying their own, in an effort to weaken the Nazi regime that they disliked. Adolf Hitler recognized the value of this man, "worth more than an army", and promoted him to Major in 1943. Koedel lived modestly on his own means and does not seem to have received much, if any, money at all from Germany. Cash transfers are a notorious opportunity for leaks in any spy operation. Koedel was finally caught on a Tax matter.